Electric propulsion unit for miniature railways



Jan. 2, 1951 H, s, BEAN 2,536,344

ELECTRIC PROPULSION UNIT FOR MINIATURE RAILWAYS Filed April 28, 1948COMMUTATOR COMMUTATOR 5 WOUND ARM ATURE INVENTOR Herbert S. B e 0 n WM fHIS ATTORNEY Patented Jan. 2, 1951 UNITED STATES PATENT OFFICE ELECTRICPROPULSION UNIT FOR MINIATURE RAILWAYS 3 Claims.

My invention relates to an electric power unit. More particularly itconcerns such a power unit having the usual fixed magnet and a rotatingarmature, in which the power developed is taken off directly from twocommutators at opposite ends of the armature. In a preferred embodi-.ment, my invention has to do with an extremely simple, small, powerunit, particularly designed for miniature railways and the like, inwhich the two commutators serve as driving wheels and draw the electriccurrent directly from the rails.

The principal object of my invention is to eliminate a number of partsof the conventional electric power unit, such as the brushes, reductiongears, etc., thereby eliminating a great deal of friction and somecommon sources of trouble. A further object is to provide a complete,self-contained power unit requiring no electrical connections other thanits driving wheels. Yet another object is to provide such a power unitwhich can easily be installed in miniature locomotives or similar toys.Additional objects and advantages of my invention will become apparentfrom the following description.

The outstanding feature of my invention resides in the provision of twocommutators at opposite ends of the armature, which act as the drivingmeans for my novel power unit. Generally these commutators serve thefunction of driving wheels and act upon a pair of conductors throughwhich the electric current is supplied to the armature. Such a pair ofconductors may, for example, be the rails upon which a miniaturelocomotive runs. However, my invention is not limited to thisapplication of my power unit, since many other applications willundoubtedly occur to those skilled in the art. The idea of employing apair of commutators as the driving means may be applied whenever thepower unit is to move with reference to a corresponding pair ofconductors from which the electric current can be drawn. The underlyingprinciple of my invention may aptly be called rolling commutation, thusdistinguishing it from the usual sliding commutation.

In order to utilize the new principle ofmy invention, it is necessarythat the conventional type of armature be modified by providing it withtwo commutators, one at each end, instead of the usual, singlecommutator. The pair of commutators so provided are connected to theconventional armature coils in such a manner that the electric currentwill flow from one segment of one commutator through an armature coil toa corresponding segment of the other commutator. This is, of course, adefinite departure from the usual practice of employing a pair ofbrushes to pass current through opposite segments of a singlecommutator.

My invention can best be described and understood by reference to theaccompanying drawings which illustrate several preferred embodimentsthereof. In these drawings:

Fig. 1 shows a perspective view of a power unit according to myinvention, riding upon a pair of rails from which the electric currentis supplied.

Fig. 2 is a detailed, cross-sectional view showing the construction ofone of the commutators of the unit shown in Fig. 1, that are used as thedriving wheels.

Fig. 3 illustrates, more or less diagrammatically and with parts brokenaway, another preferred embodiment of my invention in which a pair ofarmatures each having two commutators is employed to form a self-poweredtruck having four driving wheels.

Referring now to Figs. 1 and 2, the armature generally is represented bythe reference numeral I. Disposed about said armature is theconventional magnet 2 with its poles diametrically opposed. At the endsof the armature I are the commutators 3 and t which ride upon the rails5 and 6, respectively. These commutators are provided with flanges l andserve as the driving wheels for the power unit.

No attempt is made to show the actual coil windings of the armaturebecause these are conventional with the exception that, instead of beingconnected to opposite bars or segments of a single commutator, they areconnected to corresponding segments H and I2 of the commutator Wheels 3and 4. Thus the rails 5 and. 6 serve the function of the pair of brushesthat act upon opposite segments of the single commutator in theconventional electric power unit.

A very simple mechanical connection between the magnet 2 and the commonaxle l3 of the revolving armature l and commutator wheels 3 and 4 isprovided by the bridge M whose cut-out portions impart sufficientelasticity to the arms 46 and H to permit them to be spread to receivethe ends of the axle l3.

The detailed construction of the segmented driving wheels (commutators)3 and 4 can best be seen from Fig. 2 in which H3 represents one of thesegments. This segment is rigidly held between two discs I 9 and 29 andis insulated therefrom by the insulating layers 2! and 22. A lockingaction is provided by means of the projection 23 upon the segment I8,which fits 1nto a corresponding recess 24 in the disc l9. When 55 thewheel is tightly assembled, it will be composed of the desired number ofsegments, each insulated from its neighbors and from the axle IS.

The magnet 2 illustrated is a permanent magnet, which is the preferredtype, because it permits directional control simply by reversing thefiow of direct current. It is also possible to employ an electromagnet,in which case the magnet would have to be energized either through shoeson the rails (shunt) or through brushes acting on the tops of thecommutator wheels 3 and 4. The use of an electromagnet thus introducessome friction, additional parts and complicates directional control,since some form of relay would be required. 7

'As previously indicated, the armature I is of the conventional type,except that its coils are connected to corresponding segments of twocommutators, instead of to opposite segments of a single commutator. Itwill include a plurality of coils and poles, preferably 2, 3 or 5,depending upon the type of performance desired. It is unnecessary to gointo detail with regard to the armature windings, since these areconstructed in accordance with well-known principles, the solediiference being that the current is passed through a second commutator,instead of through a separate segment of the same commutator.

Fig. 3 illustrates an embodiment of my invention that is particularlydesigned for Diesel and power coach reproduction. It shows aself-powered truck including a pair of my new electric power units,which can be installed in a model Diesel or power coach simply byplacing the body of the coach over the upwardly projecting pin of myduplex unit.

In the duplex unit of Fig. 3 there are employed two armatures, one ofeach pair of commutator driving wheels 25 and 26 being shown. A largepermanent magnet 2'! is disposed above the two armatures with its polesfacing opposite sides of each. Between the two armatures is another,smaller permanent magnet 28 whose poles (of opposite polarity) face thesides of each armature opposite to those faced by the poles of thelarger magnet 27. A simple mechanical connection 29 (not shown indetail) is provided to maintain these parts in their properrelationship. Above the center of this mechanical connecting means andforming a part thereof is a projecting pin 56 which will fit into acorresponding opening in the body of the miniature Diesel locomotive orpower coach that is to be powered by the unit.

' train or locomotive to supply whatever amount of power may be desired.One outstanding advantage of these units for this particular purpose, isthe elimination of the very substantial friction inherent in theconventional miniature power units, due to the use of brushes andreduction gears. This enables the miniature loco- 'motives and trainsemploying my new units to coast in a realistic manner, when the electriccurrent is shut off, instead of sliding to a quick stop, as invariablyhappens when employing the conventional power units.

While I have described my new units with par- 4 ticular reference totheir use in miniature locomotives, trains and other track-bornedevices, there are many other possible applications. For example, thecommutator driving wheels could be shaped in the form of gears andimpart a positive drive to a pair of much larger meshed gears from whichthe electric current is supplied. My power unit could either rotateabout the circumference of the larger gears, owing to the absence offurther electrical connections, or it might be fixed, thus serving torotate the larger gears. Instead of large circular gears, one mightemploy a pair of conductive belts or chains upon which the commutatordriving wheels could act.

Since many widely varying embodiments of my invention are possible, itshould be understood that it is not limitedto those specificallydiscussed herein. It includes all devices embodying the novel principlesI have disclosed, coming within the scope of the appended claims, andtheir obvious equivalents.

I claim:

1. An electric power unit for miniature railways comprising a permanentmagnet, a rotatable armature between the poles thereof, and two separatecommutators mounted at opposite'ends of the armature, said commutatorshaving the form of flanged driving wheels adapted to ride upon a pair ofrails, whose flanges and bearing surfaces are divided into a pluralityof segments, each of which is insulated from the others, electricallyconnected to a coil of the armature and rigidly held between two discsforming part of the wheel, from which it is likewise insulated.

2. A self-contained electric power truck for miniature railways,comprising a relatively large, Q-shaped permanent magnet, two rotatablearmatures lying side by side between the poles thereof, and a relativelysmall I-shaped permanent magnet disposed between said armatures with itspoles directed towards opposite poles of the larger magnet, each of saidarmatures having two separate commutators mounted at opposite ends, saidcommutators having the form of flanged driving wheels, adapted to rideupon a pair of rails, the flanges and bearing surfaces of said Wheelsbeing divided into a plurality of segments each of which is insulatedfrom the others and electrically connected to the armature, saidsegments being rigidly held between clamping discs to form the wheels. 7V

3. A flanged driving wheel adapted to ride upon a rail and to act as acommutator of an electric power unit, said wheel comprising a pluralityof similarly shaped segments of conductive material, each including aportion'of the flange and bearing surface of the wheel, said segmentsbeing assembled in circular form and rigidly held between two discsforming part of the wheel, and each segment being insulated from theothers and from said discs. 7

HERBERT S. BEAN.

REFERENCES CITED The following references are of record in th file ofthis patent:

UNITED STATES PATENTS- Number Name Date 1,636,840 Sheehan July 26, 19271,862,248 Wesnigk June 7, 1932

